1. Field
The present invention relates to an improved bone anchoring system for attaching living tissue or a prosthetic device to bone.
2. Background
U.S. Pat. No. 5,584,695, the disclosure of which is also incorporated herein by reference, describes in FIGS. 7 and 8 a two-part bone anchoring system composed of an anchoring screw and a coupling pin. The anchoring screw is intended to be screwed into a hole previously drilled into the bone. The coupling pin includes a shank shaped to be received in a bore hole in the anchoring screw and, on its proximal end, an eyelet for receiving and holding a suture or prosthetic device. The shank of the coupling pin is made from a material which expands in response to body heat, thereby locking the coupling pin in place in the bore hole of the anchoring screw.
Self-tapping cannulated bone screws are also known. See, for example, U.S. Pat. No. 5,516,616 and U.S. Pat. No. 5,571,139, the disclosures of which are also incorporated herein by reference.
Although the anchoring systems of these patents provide some advantages over earlier technology, there is still a need to provide more secure anchoring, greater flexibility and simpler operation than possible in these systems.
This and other objects are accomplished by the present invention in accordance with which a new bone anchoring system is provided. This system is composed of a novel self-boring, self-tapping bone screw configured to enhance bone growth and a mechanical insert for mounting in the bone screw. The insert can carry different attaching structures for attachment to suture thread, tissue or other prosthetic device and can be mounted in the bone screw in a variety of different ways. By this means, the inventive anchoring system can be arranged in a variety of different configurations simply and easily and yet still provide secure mounting in all configurations.
Thus, the present invention provides a new bone anchoring system comprising a bone screw defining a self-tapping, self-boring tip and a central bore, and a mechanical insert having a distal end for being received in the central bore and mechanically held by the bone screw, the insert further having a proximal end defining an attachment structure for securing to suture thread, tissue or other prosthetic device, wherein the bone screw includes at least one opening for receipt of new bone growth when the bone screw is screwed in place in a bone.